Hydraulically actuated detent mechanism

ABSTRACT

A hydraulically actuated detent mechanism for positioning an elongated spool in the bore of a control valve has circumferentially spaced apart, radial bores opening at their inner ends to the valve bore and having their outer ends in communication with a source of fluid pressure, a detent plunger arranged in each of the radial bores and tending to be urged into balanced detent engagement with axially spaced apart depressions in the spool by fluid pressure in the outer ends of the radial bores. Preferably, the detent mechanism also includes kickout means which are operable for releasing the spool from detent engagement through the introduction of fluid pressure into the inner ends of the radial bores.

U United States Patent [191 [111 3,869,107 Field, Jr. et al. v Mar. 4,1975 HYDRAULICALLY ACTUATED DETENT MECHANISM V [57] ABSTRACT [75]lnvemors' g fi g flgi g "kggg g l fif Glen A hydraulically actuateddetent mechanism for positioning an elongated spool in the bore of acontrol [73] Assignee: Caterpillar Tractor Co., Peoria, lll. valve hascircumferentially spaced apart, radial bores [22] Filed, Sept 4 1973opening at their inner ends to the valve bore and having their outerends in communication with a source I21] Appl. No.: 394,189 of fluidpressure, a detent plunger arranged in each of I the radial bores andtending to be urged into balanced 52 us. Cl. 251/94, 251/297 lengagement axially SPaCed apart depres' [51] Int. Cl. Fl6k 35/00 slons mspool by mud pressure m the Outer of 581 Field of Search 251/94 297-137/624 27 the bmes' Preferably the mechansm also includes kickout meanswhich are operable 'for [56] References Cited rfileasingdthespootl fflrozii detent engagehment through t 6 intro uctlon 0 Ul ressure into I einner en 5 UNITED STATES PATENTS of the radial bores. p 2,844,166 7/1958Edman 251/94 X 8 Claims, 2 Drawing [Figures 48 18 3 CONTROL VALVE 28 4537 gll -26 -19 T I 52 Y) 1 55 51 in I 1 HYDRAULICALLY ACTUATED DETENTMECHANISM BACKGROUND OF THE INVENTION The present inventionrelates to adetent mechanism of the type having a plurality of detent plungersarranged in circumferentially spaced apart relation for detentengagement witha valve spool. Y

Many hydraulic control valves employ'detent mechanisms of the typegenerally contemplated by the present invention for maintaining thespool of the control valve in a preselected position. It is also commonto employ a kickout device for releasing the detent mechanism andallowing the spool to be repositioned or to return to a neutralposition.

Within such detent mechanisms, detent elements such as plungers or ballbearings are spring-loaded for resilient engagement with angular groovesor ridges in the control spool and thus tend to maintain the spool inone or more preselected positions. In many such valves, two or moredetent elements are arranged in opposition to each other for balancedengagement with the spool. Detent arrangements of this type are intendedto provide balanced forces acting upon the spool and thus allow freertravel of the spool in its bore.

However, even with such balanced arrangements, various factors stilltend to result in side loading of the spool and thus interfere withmovement of the spool in its bore. The most prevalent causes ofunbalanced forces have been foundto include manufacturing tolerancesrelating to both the valve body and spool as well as variations in thelength and load rate for springs associated with different detentelements.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to overcome one or more problems of the type described abovethrough the use of a plurality of detent elements arranged for balancedinteraction with a valve BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is agenerally schematic representation, with parts in section, of ahydraulic control circuit including a pilot control valve having a spooltending to be positioned by a detent mechanism constructed according tothe present invention.

FIG. 2 is a fragmentary view, with parts in section, of a controlcircuit similar to that of FIG. 1 while representing another embodimentof the detent mechanism of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydraulic control circuit ofthe type illustrated in FIG. 1 is particularly adapted for operation ofa hydraulic motor such as the double-acting jack indicated at 11. Thejack 1! includes a cylinder 12 having a pis- LII ton 13 slidablyarranged therein and a connecting rod 14 which penetrates one end of thecylinder 12. Hydraulic fluid under pressure for operating the jack 11 isprovided by a pump 16 which draws fluid from a reservoir I7 and directsit to a control valve l8 thr0ugh a conduit 19. A relief valve 21arranged in a branched conduit 22 establishes operating fluid pressurein the conduit 19.

Fluid conduits 23 and 24 communicate the control valve 1 8 respectivelywith the head end and rod end of the cylinder 12. The control valve 18is also in communication with the reservoir 17 through another conduit26.

The control valve 18 is of a conventional type adapted for response topilot fluid communicated thereto by pilot conduits 27 and 28. Forexample, when pilot fluid pressurizes the conduit 27, the control valve18 communicates fluid under pressure from the conduit 19 to the head endof the cylinder 12 through the conduit 23 while the rod end of thecylinder is communicated to the reservoir 17 through the conduits 24 and26. Similarly, the control valve 18 responds to pilot pressure in theconduit 28 for communicating fluid pressure from the conduit 19 towardthe rod end of the cylinder through the conduit 24 while the head end ofthe cylinder is communicated to the reservoir through the conduits 23and 26. In the absence of pilot pressure in either of the conduits 27and 28, the control valve 18 tends to assume a neutral position withboth ends of the cylinder 12 being hydraulically closed.

An actuator extension 29 of the rod 14 supports actuating cams 31 and 32which are arranged to respectively engage rotary valves 33 and 34 forperforming a kickout function in a manner described in greater detailbelow.

Pilot operation of the control valve 18 is regulated by a pilot controlvalve 36 which has an elongated spool 37 arranged for axial movement ina bore 38 to regulate the passage of pilotfluid thereacross. The spool37 tends to be positioned in a neutral condition as illustrated in FIG.1 .by means of a conventional centering spring mechanism as indicated at39.

Pilot fluid pressure is provided by a pump 41 which draws fluid from thereservoir 17 and communicates it through a pilot inlet conduit 42wherein pressure is established by a relief valve 43, The pilot controlvalve 36 forms a number of fluid ports which are in communication withits valve bore'38 and with other components of the pilot controlcircuit. A centrally arranged inlet port 44 is in communication with apilot inlet conduit 42. Pilot service ports or chambers 46 and 47areaxially spaced along the bore 38 on opposite sides of the inlet port44 while being in respective communication "with the control valve 18through the conduits 27 and 28. Drain ports 48 and 49 are respectivelyspaced apart from the service ports 46 and 47 while being incommunication with the reservoir 17 through a drain conduit 51.

A detent mechanism constructed according to the present invention isgenerally indicated at 52 for positioning the spool 37 within the bore38. The detent mechanism comprises a pair of radially extending bores 53and 54 which are arranged in circumferentially spaced or diametricallyopposed relation to the bore 38. The inner ends of the radial bores 53and 54 communicate with the axial bore 38 while the outer ends of thetwo radial bores are in common communication 3 with pilot fluid pressurein the inlet conduit 42 by means of a branched conduit 56.

An elongated detent element or plunger 57 is slidably arranged withineach of the radial bores and thus tends to be urged radially inwardlytowards the spool 37 by means of fluid pressure entering the outer endsof the radial bores 53 and 54 from the common conduit 56. The taperedinner ends of the detent plungers 57 thus tend to enter into detentengagement with opposed sets oftlepressions or indentations 58 and 59which are formed in axially spaced apart relation along the spool 37.The respective depressions 58 and 59 are located upon the spool 37 sothat when they are engaged by the detent plungers 57, the pilot spool 37is positioned within the bore 38 to communicate pilot fluid to thecontrol valve through one of the conduits 27 and 28.

Preferably, each set of depressions 58 and 59 comprisescircumferentially spaced apart indentations of relatively greater depthwith axially extending deformations 61 of relatively lesser depth in thespool 37 interconnecting the angularly aligned and axially spaced apartdepressions 58 and 59. Through this arrangement, the detent plungers 57serve to prevent angular rotation of the spool 37 within its bore 38.

As noted above, the detent mechanism 52 is responsive to operation ofthe rotary valves 33 and 34 to release the detent engagement of thespool 37 and allow it to be returned to its neutral position as shown bythe centering spring mechanism 39. The rotary valves 33 and 34 are ofsimilar construction and accordingly only the components of one valveare described below, the similar components of the other valve beingindicated by corresponding numerals. The valve 33 receives pilot fluidpressure from the inlet conduit 42 through a branched conduit 62. Thevalve includes a rotatable spool 63 forming both-a pressure passage 64and a vent along the axial deformation 6] to.act upon the inner ends ofthe plungers 57 and balance fluid pressure acting on the outer ends ofthe plungers 57 from the conduit 56. Accordingly, the spool 37 is freefrom detent engagement with the plungers 57 so that it may be returnedto its neutral position shown in FIG. I by the centering springmechanism 39.

'Similarly, the port 74 remains in communication with the inner ends ofthe plungers 57 during extension of the hydraulic jack 11. Maximumextension is similarly signalled by engagement of the cam 32 with thelever 69 of the valve 34. Fluid pressure is communicated by the valve 34through the conduit 73 and the port 74 to similarly act upon the innerends of the detent plungers 57 and again permit the spool 57 to bereturned to its centered position by the spring mechanism 39.

Another embodiment of the detent mechanism is illustrated in FIG. 2. Thedetent mechanism of that fig ure is substantially similar to themechanism described above with reference to FIG. 1. Accordingly,components in the detent mechanism of FIG. 2 which correspond tocomponents in FIG. 1 are indicated by similar primed numerals.Generally, the detent mechanism of passage 66 to provide selectivecommunication be- I 63 is controlled by a depending lever 69. Normallythe spool 63 is positioned to communicate the outlet port 67 with, thedrain conduit 68 by means of the vent passage 66. However, as the lever69 of the valve 33 is urged l'eftwardly by the cam 31, the spool 63 isrotated to a position where the pressure passage 64 communicates theinlet conduit 62 with the outlet port 67. The outlet port 67 of thevalve 33 is in communication through a conduit- 71 with the pilotcontrol valve bore '38 through a port 72 which is generally in alignmentwith-the depressions 58 when the spool is in its neutral position. v

The other rotary valve 34 is similarly responsive to rightward movementof the cam 32 to communicate the branched conduit 62 through its outletport 67 to another conduit 73. The conduit 73 is similarly incommunication with the pilot control valve bore 38 through a port 74which is generally in alignment with the depressions 59 when the spool37 is in its neutral position. Through the positioning of the ports 72and 74 and the arrangement of the axial deformation .61, it may be seenthat the port 72 remains in communication with the inner ends of theradial bores 53 and 54 during retraction of the hydraulic jack 11.Maximum desired retraction of the jack 11 is indicatedwhen the cam 31engages the lever 69. Thereafter, the valve 33 communicates fluidpressure through the conduit 71. That fluid pressure is communicatedthrough the port 72 and FIG. 2 ismodified to provide an automatickickout function only when the spool 37' is shifted upwardly as viewedin the figures for engagement of the detent plungers 57' with theopposed depressions 59'.

It may be further seen that the detent mechanism of FIG. 2 does notinclude an inlet port corresponding to' that shown at 74 in FIG. 1. Whenthe spool 37' is moved downwardly to the position shown, the inlet port72 is blocked from communication with the inner It may of course be seenin FIG. 2 that when the spool 37' is shifted upwardly and thusconditions the control valve for retracting operation of the jack 1],kickout fluid pressure is communicated against the inner ends of thedetent plungers 57' through the port 72' in a manner similar to thatdescribed above with reference to FIG. 1.

We claim:

1. A hydraulic detent mechanism in a control valve having an elongatedspool axially movable in a bore of a valve body for regulating fluidcommunication with a motor means, comprising a portion of the spoolforming axially spaced apart depressions,

the valve body forming a plurality of circumferentially spaced apart,radial bores communicating at their inner ends with the valve bore andat their outer ends with a common pressurizedfluid conduit,

a detent plunger slidably arranged in each of the radial bores, thedetent plungers tending to be urged into balanced detent engagement withthe depressions in the spool by fluid pressure in the outer ends of theradial bores.

2..The detent mechanism of claiml further comprising detent kickoutmeans operable for selectively communicating fluid pressure into theinner ends of the ra- I trol valve comprises a centering mechanismtending to urge the spool into a selected position within the valvebore, common fluid inlet means communicating fluid at substantially thesame pressure to the outer ends of the radial bores and to the kickoutmeans for selective communication to the inner ends of the radial bores.

5. The detent mechanism of claim 2 wherein the motor means is ahydraulic jack having a piston movable within a cylinder, the kickoutmeans being associ ated the the jack and responsive to-movement of thepiston toward a preselected position in the cylinder.

6. A pilot operated valve assembly for regulating operation of ahydraulic motor, with a main control valve for selectively communicatingfluid to the motor and a pilot valve for selectively communicating pilotfluid from a pilot inlet to the main control valve, the pilot valvecomprising a valve body forming a bore, a spool arranged in the bore foraxial movement to selectively regulate fluid flow from the pilot inletto the main control valve, means coupled with the spool for axiallypositioning it in the bore, and a hydraulic detent mechanism including aportion of the pilot valve spool with axially spaced apart depressionsformed therein, a plurality of circumferentially spaced apart, radialbores communicating at their inner ends with the pilot valve bore and attheir outer ends with the pilot fluid inlet and a detent plungerslidably arranged in each of the radial bores, the detent plungerstending to be urged into balanced engagement with the depressions in thepilot valve spool by pilot inlet fluid pressure.

7. The pilot operated valve assembly of claim 6 further comprisingkickout valve means for limiting opera tion of the motor, the kickoutvalve means selectively communicating inlet pilot fluid pressure to theinner ends of the radial bores.

8. A pilot control valve for selectively communicating pilot fluidpressure through first and second conduits to a main control valve forregulating operation of a double-acting hydraulic motor, comprising avalve body defining a valve bore,

an elongated spool including resilient centering means tending toposition the spool in a neutral condition, the spool being axiallymovable in opposite directions for communicating a source of fluidpressure with the first and second conduits respectively,

the valve body forming a plurality of circumferentially spaced apart,radial bores communicating at their inner ends with the valve bore andat their outer ends with a common pressurized fluid conduit, and

a detent plunger slidably arranged in each of the ra dial bores forbalanced detent engagement with the spool under the influence of fluidpressure in the outer ends of the radial bores.

a portion of the spool forming a plurality of a depressions, thedepressions being axially spaced from each other to receive the detentplungers when the spool is positioned to communicate fluid to either ofthe first and second conduits and detent kickout means operable forselectively communicating fluid pressure into the inner ends of theUNITED STATES PATENT OFFICE QETIFICATE 0F CORRECTION PATENT NO. 3, 9, 7DATED March t, 1975 mvmrorzrs JESSE L. FIELD, JR. nd GIENYJ-"MEDINA Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Claim 5 should be omitted since it was withdrawn following a restrictionrequirement.

Claim 6 was properly allowed within this case and should be added toread as follows:

60 The detent mechanism of Claim 1 wherein the axially spaced apartdepressions comprise circumferen-tially spaced apart indentations ofrelatively greater depth for O alignment with the respective detentplungers,

circumferentially spaced apart and axially extending deformations ofrelatively lesser depth in the spool connecting the indentations tomaintain angular alignment of the spool in the valve bore.

Signed and Sealed this ninth D a Of December I 9 75 '[SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN 14179311718 ff Commissioner of Parentsand Trademarks

1. A hydraulic detent mechanism in a control valve having an elongatedspool axially movable in a bore of a valve body for regulating fluidcommunication with a motor means, comprising a portion of the spoolforming axially spaced apart depressions, the valve body forming aplurality of circumferentially spaced apart, radial bores communicatingat their inner ends with the valve bore and at their outer ends with acommon pressurized fluid conduit, a detent plunger slidably arranged ineach of the radial bores, the detent plungers tending to be urged intobalanced detent engagement with the depressions in the spool by fluidpressure in the outer ends of the radial bores.
 2. The detent mechanismof claim 1 further comprising detent kickout means operable forselectively communicating fluid pressure into the inner ends of theradial bores and thereby tending to urge the detent plungers out ofengagement with the spool.
 3. The detent mechanism of claim 2 furthercomprising means for providing fluid drainage from the inner ends of theradial bores other than when the detent kickout means is communicatingfluid pressure thereto.
 4. The detent mechanism of claim 2 wherein thecontrol valve comprises a centering mechanism tending to urge the spoolinto a selected position within the valve bore, common fluid inlet meanscommunicating fluid at substantially the same pressure to the outer endsof the radial bores and to the kickout means for selective communicationto the inner ends of the radial bores.
 5. The detent mechanism of claim2 wherein the motor means is a hydraulic jack having a piston movablewithin a cylinder, the kickout means being associated the the jack andresponsive to movement of the piston toward a preselected position inthe cylinder.
 6. A pilot operated valve assembly for regulatingoperation of a hydraulic motor, with a main control valve forselectively communicating fluid to the motor and a pilot valve forselectively communicating pilot fluid from a pilot inlet to the maincontrol valve, the pilot valve comprising a valve body forming a bore, aspool arranged in the bore for axial movement to selectively regulatefluid flow from the pilot inlet to the main contRol valve, means coupledwith the spool for axially positioning it in the bore, and a hydraulicdetent mechanism including a portion of the pilot valve spool withaxially spaced apart depressions formed therein, a plurality ofcircumferentially spaced apart, radial bores communicating at theirinner ends with the pilot valve bore and at their outer ends with thepilot fluid inlet and a detent plunger slidably arranged in each of theradial bores, the detent plungers tending to be urged into balancedengagement with the depressions in the pilot valve spool by pilot inletfluid pressure.
 7. The pilot operated valve assembly of claim 6 furthercomprising kickout valve means for limiting operation of the motor, thekickout valve means selectively communicating inlet pilot fluid pressureto the inner ends of the radial bores.
 8. A pilot control valve forselectively communicating pilot fluid pressure through first and secondconduits to a main control valve for regulating operation of adouble-acting hydraulic motor, comprising a valve body defining a valvebore, an elongated spool including resilient centering means tending toposition the spool in a neutral condition, the spool being axiallymovable in opposite directions for communicating a source of fluidpressure with the first and second conduits respectively, the valve bodyforming a plurality of circumferentially spaced apart, radial borescommunicating at their inner ends with the valve bore and at their outerends with a common pressurized fluid conduit, and a detent plungerslidably arranged in each of the radial bores for balanced detentengagement with the spool under the influence of fluid pressure in theouter ends of the radial bores, a portion of the spool forming aplurality of a depressions, the depressions being axially spaced fromeach other to receive the detent plungers when the spool is positionedto communicate fluid to either of the first and second conduits anddetent kickout means operable for selectively communicating fluidpressure into the inner ends of the radial bores.